A conventional television receiver has a nominal 4:3 aspect ratio (the ratio of width to height). Recently, there has been interest in using wider aspect ratios for television systems, such as 2:1 or 5:3, which more nearly approximate or equal the aspect ratio of the human eye than does the conventional 4:3 ratio. The 5:3 aspect ratio has received particular attention since release prints for motion picture film in the United States use this ratio, and thus can be transmitted and received without cropping. However, wide-screen television systems which simply transmit signals having an increased aspect ratio as compared with conventional systems are incompatible with conventional aspect ratio receivers. This makes widespread adoption of wide-screen systems difficult. It is, therefore, desirable to have a wide-screen television system that is compatible with conventional television receivers. In accordance with the principles of the present invention a wide-screen television system is provided that is compatible with conventional television receivers.
This compatability allows a viewer to display a 4:3 aspect ratio picture on a conventional receiver without modifying the conventional receiver. On the other hand, the viewer who desires to receive and display the wide angle television signals will have to have a new receiver. It is desirable that a new receiver capable of displaying wide angle pictures be multi-purpose, that is, capable of receiving and displaying both standard and wide aspect ratio signals. Initially receiver manufacturers may not wish to invest in special tooling and equipment to produce wide-angle kinescopes.
It has been suggested to fully scan a standard definition, 4:3 aspect ratio, kinescope when a standard definition television picture is displayed and to collapse the vertical deflection somewhat to display the wide-angle picture when available. This scheme, while logical, means that the customer (viewer) buying an expensive multi-function receiver displays the "better" wide-angle picture on a display smaller than on the standard definition display. Psychologically, the customer is spending more but getting less.
In accordance with one aspect of the present invention, a special wide-angle receiver is equipped with a standard 4:3 aspect ratio kinescope which is permanently masked to provide a wide-angle display. The new receiver has a wide-angle aspect ratio viewing area for displaying wide-angle pictures. In this mode of operation the viewing area of the wide-angle display is fully scanned during presentation of wide-angle pictures. On the other hand, when a standard definition, 4:3, picture is being viewed, the horizontal deflection (and only the horizontal deflection) is collapsed thereby displaying a standard definition 4:3 aspect ratio picture on an area smaller than the full width of the wide-angle display. Consequently, when the viewer views a wide-angle picture in the wide-angle mode he sees more picture than in the standard-definition mode.